Digital images are well known and are generated in many ways, such as from a digital camera or video camera (whether operated automatically or by a human photographer), or scanning of a photograph into digital format. The digital images vary in their quality, depending on the abilities of the photographer as well as on the selected exposure, the selected focal length and the lighting conditions at the time the image is taken.
Digital images may be edited in various ways to improve them. For example, the image may be sent through a processor which may enhance the sharpness of the image by increasing the strength of the high frequency components. However, the resultant image may have an increased level of noise, spurious oscillations known as “ringing” which are caused by overshooting or undershooting of signals and image independent sharpness enhancement that results in an incorrect change in sharpness.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.